Why does the editor issue a warning whether I delete or replace the UID? How can I deal with these warnings?

    TerrorMan What do you mean by "delete or replace the UID"? Are you manually giving new UIDs to resources? Please explain in more detail what you are doing and why.

    Also try closing Godot, deleting your .godot directory and open the project again.

    TerrorMan deleting files from file folder is not reccomended, you mess up dependencies and godot cant resolve them. Not sure about uids